Regulation of glial cell line-derived neurotrophic factor release from rat C6 glioblastoma cells.
We have monitored glial cell line-derived neurotrophic factor (GDNF) secretion from rat C6 glioblastoma cells by ELISA. Representative cytokines, neurotrophins, growth factors, neuropeptides, and pharmacological agents were tested for their ability to modulate GDNF release. Whereas most factors tested had minimal effect, a 24-h treatment with fibroblast growth factor-1, -2, or -9 elevated secreted GDNF protein levels five- to 10-fold. The proinflammatory cytokines interleukin-1beta, interleukin-6, tumor necrosis factor-alpha, and lipopolysaccharide elevated GDNF release 1.5- to twofold. Parallel studies aimed at elucidating intracellular events that may regulate GDNF synthesis/release demonstrated the involvement of multiple signaling pathways. GDNF levels were increased by phorbol 12,13-didecanoate (10 nM) activation of protein kinase C, the Ca2+ ionophore A23187 (1 microM), okadaic acid (10 nM) inhibition of type-2A protein phosphatases, nitric oxide donors (1 mM), and H2O2 (1 mM)-induced oxidative stress. Elevation of cyclic AMP levels by either forskolin (10 microM) or dibutyryl cyclic AMP (1 mM) repressed GDNF secretion, as did treatment with the glucocorticoid dexamethasone (1 microM). Our results demonstrate that diverse biological factors are capable of modulating GDNF protein levels and that multiple signal transduction systems can regulate GDNF synthesis and/or release.
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Department of Molecular and Cellular Biochemistry, Center for Biological Research, Roche Bioscience, Palo Alto, California 94304-1397, USA.
Wyatt
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TL
Hajos
B
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Eglen
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Baecker
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Johnson
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RM
D000818:Animals; D016207:Cytokines / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D051100:Glial Cell Line-Derived Neurotrophic Factor; D005909:Glioblastoma / Q000378:metabolism*; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D009414:Nerve Growth Factors / Q000096:biosynthesis; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D009479:Neuropeptides / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011453:Prostaglandins / Q000494:pharmacology; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014407:Tumor Cells, Cultured
D016207:Cytokines; C495039:GDNF protein, human; C495041:Gdnf protein, rat; D051100:Glial Cell Line-Derived Neurotrophic Factor; D006133:Growth Substances; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D011453:Prostaglandins; D011994:Recombinant Proteins